Hallucinating the past: a case of spontaneous and involuntary recall of long-term memories: perspectives on the hemispheric organization of visual memory.

This paper presents the unique case of a patient who developed palinopsias and formed visual hallucinations, representing spontaneous recall of memories from a discrete 10-year time period. The visual phenomena began shortly after the initiation of prophylactic whole-brain radiation therapy, following the removal of a metastatic adenocarcinoma in the region of the right cuneus. The most striking feature of this patient's hallucinations is the composition: memories from a discrete 10-year time period from about 30 years ago. This case provides further evidence to support the theory of a contralateral and hemispheric organization of visual memory. We propose that visual memory traces formed nearly three decades ago were spontaneously recalled in the form of hallucinations and palinopsias. It is noteworthy that the region of the brain most affected by the tumor and subsequent radiation therapy is postulated to permit perception of mental imagery. To our knowledge, no other case involving hallucination of 30-year-old memories has been reported.